Bedside Tool May Flag Brain Dysfunction in the Critically Ill

Key Takeaway

  • A preliminary, unpublished study that used noninvasive diffuse correlation spectroscopy (DCS) to assess cerebral blood flow (CBF) in patients undergoing extracorporeal membrane oxygenation (ECMO) showed that comatose patients have increased cerebral hemispheric perfusion asymmetry compared to noncomatose patients. The findings suggest hemispheric asymmetry may be a biomarker of neuronal dysfunction and that DCS may be a useful noninvasive method of identifying it.

  • The study is a preprint and has not been peer-reviewed.

Why This Matters

  • Performing accurate neurologic examinations in this patient population is challenging. Neuroimaging requires resource-intensive transportation to imaging suites, while invasive neuromonitoring can further increase the risk of cerebral hemorrhage. As a result, the brain’s perfusion and oxygenation requirements are not routinely monitored, furthering the potential for injury.

Study Design

  • The study included 13 adult patients (five females, mean age 46 years) admitted to the cardiac intensive care unit for ECMO therapy. Seven patients required ECMO for cardiac arrest, four for cardiogenic shock, and two for acute respiratory distress syndrome (ARDS).

  • All received continuous bedside neuromonitoring with DCS, which uses near-infrared light to measure cortical CBF.

  • Based on Glasgow Coma Score motor (GCS-M) scores, nine patients (69%) were classified as “awake” (GCS-M > 4) and four (31%) as “comatose” (GCS-M ≤ 4).

  • Patients underwent daily CBF monitoring using a DCS system. Personnel continuously recorded physiologic data including systolic, diastolic, and mean arterial pressure (MAP).

Key Results

  • Comatose patients had more interhemispheric relative cerebral blood flow (rBF) asymmetry (ASYMrBF) compared to noncomatose patients over a range of mean arterial pressure (MAP) values (29% vs 11%, P = .009).

  • ASYMrBF in comatose patients resolved in a MAP range of 70–80 mm Hg, while rBF remained symmetric through a wider MAP range in noncomatose patients.

  • According to investigators, this is the first use of DCS to measure cerebral perfusion noninvasively in this patient population.


  • The study sample size is small and precluded the ability to analyze these factors as covariates for association between ASYMrBF and GCS-M.

  • Further larger studies are needed to validate hemispheric asymmetry as a biomarker of neuronal dysfunction.

  • It remains to be seen whether this marker predicts coma recovery, informs pathophysiology, or provides a goal for targeted ECMO therapy.

  • The study is a preprint and has not been peer-reviewed.

Study Disclosures

  • No disclosures

This is a summary of a preprint study by Imad Khan and colleagues from the University of Rochester Medical Center, New York, on bioRxiv provided to you by Medscape. The research has not yet been peer-reviewed. The full text of the study can be found here.

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